Another 4x4 engagement question

Everyone, I apologize if this seems like a broken record thread. I've had my Taco for a little over a year now. When I bought it, I had a shop in Vegas and the 4x4 knob worked, seemed a little slow. I have forgotten to regularly engage the 4x4 knob and now all I get it the blinking green 4 wheel and the blinking 4 low. I took off the transfer-case solenoid and "on the bench" the motor works and turn the gear. On the Taco I cannot hear anything.
1. Can the transfer-case solenoid run if the front differential solenoid is not functioning?
2. If the dial is bad, are they rebuildable or just buy another one?

Thanks gentlemen

 

Were all the limit switch contacts good?
Did you get it timed correctly when you reinstalled it?

Grab you a voltmeter and some backprobes and check the limit switch voltages at the 4wd ECU, that will give us an idea where to start looking.

https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

Appreciate all the input and the write ups!!
1- Contacts were like new
2- Seem to have clocked it appropriately (3 O'clock position?)
3- Will check the 4wd ecu with the wonderful information provided!!
Thank you

 

No problem, post your results so I can maybe help further.

 

No! The ADD first needs to “activate” before the 4WD ECU will allow the tcase to send power to the front diff. It sounds like your problem may be the ADD motor that hangs off the front diff. It’s prone to corrosion on the contacts but can be cleaned/soldered pretty easily.

edit: I had that backwards; see below

 

Actually the 4wd ECU shifts the Transfer Case first and then the ADD when both engaging and disengaging 4wd, it only shifts the ADD once the transfer case has completed it's shift.
A problem in either one can cause a flashing 4wd light but typically the only time the 4lo light will flash is when there's a problem in the transfer case limit/detection switch circuits.

 

Ah dang, you’re right! Brain fart! Guess it would have to so that the spider gears stop spinning in opposite directions lol. Not sure what tf I was thinking there for a minute…
But he’s saying 4hi isn’t engaging either, so I still think ADD actuator

 

Could be but the system locks itself out when one or more of the limit switches are out of range from where it expects them so any error in the system will cause a lockout and flashing light(s).
That's why when the light(s) are flashing I would like to know the voltages on the limit switches so we kinda have an idea of where to start without even crawling under the truck. For example if they were all at 12v we would want to check the voltage on the ground at connector PA Pin 18.

 

Outstanding information Gentlemen. Thank you